About OpticMath
OpticMath.online is a free photography calculator hub built for working photographers, filmmakers, students and educators. Every major optical and exposure calculation has its own dedicated page so you can open the tool you need, enter real camera data and leave with numbers you can use on set or in the field. The project focuses on clarity: standard formulas, camera and sensor presets, and short explanations that connect the math to practical decisions about depth of field, exposure, flash, storage and print.
Unlike generic unit converters, these tools are organized the way photographers think—around lenses, sensors, light and media. You can compare full-frame and crop bodies, solve the exposure triangle when one setting is locked, estimate how many RAWs fit on a card, or plan a night-sky shutter speed before the stars trail. All calculators run in your browser with no account and no upload of images.
How to use the calculators
Open any tool from the homepage grids or the popular shortcuts above. Each page follows the same pattern: choose a camera preset when sensor size matters, enter focal length, aperture, distance, bitrate or other inputs, then press Calculate. Results appear in the panel beside the form. Adjust the inputs and calculate again to compare scenarios—for example, f/1.8 versus f/4 at the same focus distance, or a 35 mm lens on full frame versus APS-C.
For depth of field and field of view, start with the body you actually own (Canon R5, Sony A7 IV, Fujifilm X-T5, and many others are listed). The preset fills sensor dimensions and crop factor automatically. Use Custom sensor when you need an exact width and height. Switch distance units between meters and feet when planning focus marks with a crew that prefers imperial measures.
Exposure tools share one language: exposure value (EV). Compute EV from aperture, shutter and ISO, or solve for any one of the three when the other two and a target EV are known. That workflow matches how light meters and textbooks describe equivalent exposures. Flash tools use guide numbers; storage tools use file size and bitrate; print tools use pixels and DPI. Read the short formula and FAQ under each calculator if you want to verify the model or explain it to a student.
Calculators we offer
Optics. Depth of field (near focus, far focus, total DOF, hyperfocal), hyperfocal distance alone, field of view (horizontal, vertical, diagonal), crop factor, full-frame equivalent focal length, and macro magnification. These pages answer framing and sharpness questions before you set up the tripod.
Exposure. Combined exposure calculator, dedicated EV calculator, and solvers for aperture, shutter speed and ISO. Reciprocal-rule guidance helps choose a minimum handheld shutter for a given focal length and crop factor.
Flash. Guide number relationships between distance and f-number, plus flash distance estimates for a stated GN and aperture—useful starting points before modifiers and bounce change the effective output.
Storage and printing. Photo file size estimates from megapixels and bit depth, memory-card capacity in number of frames, print size from pixel dimensions and DPI, and DPI/PPI from print size. Video file size from bitrate and duration supports card planning on set.
Astrophotography. Classic 500 rule and a stricter NPF-style exposure limit that factors crop and pixel pitch so high-resolution bodies do not trail stars as easily.
Sensor reference. Quick lookup of dimensions, diagonal and crop factor for common formats and named cameras.
Why accurate optics math matters
Guessing depth of field costs time when a client reviews files and the eyes are soft, or when a landscape foreground is mushy. Guessing exposure costs highlight detail or forces heavy noise reduction. Card shortages on a wedding day are avoidable with a realistic file-size plan. OpticMath will not replace a meter, a histogram or your taste—but it reduces avoidable uncertainty so you can spend attention on timing, light and people.
All formulas follow widely taught photographic models: circle-of-confusion based DOF, arctangent field of view, EV from N, t and ISO, guide number geometry, and bitrate × time for media. Defaults such as CoC = diagonal/1500 are stated on the page so you can interpret results for large prints or critical focus pulling.
FAQ
Are these calculators free?
Yes. OpticMath.online is free to use in the browser. No subscription is required for the core tools.
Do you store my settings or photos?
No. Calculations run locally in your browser. We do not ask you to upload images for DOF or exposure tools.
Which camera should I pick in the list?
Choose the closest body or sensor format you use. If your exact model is missing, pick the matching format (Full Frame, APS-C Canon 1.6×, APS-C 1.5×, Micro Four Thirds) or enter custom width and height in millimeters.
Why does my result differ slightly from another app?
Circle of confusion, rounding and whether hyperfocal includes the “+ f” term vary between implementations. Trends—stop down to deepen DOF, wider FOV at shorter focal length—remain consistent. Use one system for comparative decisions.
Can I use OpticMath for video and cinema?
Yes. Depth of field, FOV and exposure math apply to motion work. Video file size helps plan media. Shutter-angle workflows still map to exposure time once you convert angle and frame rate to seconds.
Is this a substitute for a light meter?
No. A meter reads the scene; these calculators interpret settings and geometry. Together they are stronger than either alone.
Getting the most from OpticMath
Bookmark the depth of field and exposure pages if those are your daily needs. Use related links at the bottom of each calculator to jump between FOV, crop factor and equivalent focal length when you switch bodies. When teaching, project a calculator page and change one input at a time so students see near focus move before they memorize the formula. When packing for a trip, run memory-card and file-size estimates once with your typical megapixels and JPEG/RAW mix so spare cards are a plan rather than a hope.
Photography rewards preparation. OpticMath exists to make the quantitative part of that preparation fast, transparent and free—so the creative part gets more of your time.